includes all sources of household discharges into sewers, industrial
effluent discharge and stormwater inflows. A typical wastewater
treatment plant is therefore required to treat a variety of
constituents including pathogenic microorganisms, suspended matter,
dissolved metals, fats and oils, organic compounds that may be
volatile, hazardous or carcinogenic and nutrients that may stimulate
the growth of a variety of nuisance algae and plants. In addition the
odour and colour of wastewater may require a treatment regime.
treatment plants deliver performance to the tertiary level of treatment
standards. This standard indicates compliance in the removal of both
nutrients and suspended solids to a low level and the removal of
biodegradable organics. Odorous constituents such as Ammonia compounds
are also converted in the process.
Through disinfection of the
treated wastewater, re-use strategies have been adopted for water to be
distributed to downstream users including irrigation, farming, energy
and industrial applications.
The re-cycling of treated and
disinfected wastewater back into the potable water distribution system
is being adopted in many cities. The combination of advanced biological
treatment of wastewater coupled with Reverse Osmosis membrane
treatments and disinfection provides a multiple barrier approach in the
risk management strategies for the delivery of safe re-useable water.